In order to improve the efficiency of wind power stations, the hubs are being arranged at ever increasing heights and larger rotors and more powerful generators are being used. This requires tower segments with increasingly larger diameters and greater wall thicknesses, so that the towers of wind power stations have sufficient rigidity, buckling resistance, and fatigue strength. Already prefabricated tubular tower segments whose diameter significantly exceeds a certain value, such as 4.4 m, can only be transported with tremendous expense to the installation site of the wind power station. This is especially due to the width of the available roads for the transport and to the clearance heights of the bridges along the way. But even transport by waterways is extremely costly in the case of large tower segments.
One possible approach to a solution, which is proposed for example in DE 603 17 372 T2 and also in WO 2009/048955 A1, is the so-called lengthwise oriented construction, which is employed especially in the lower region of the tower. Here, arc-shaped tower sections are transported to the construction site and then assembled there into tubular tower segments. The connection of the arc-shaped tower sections can be done by screw fasteners with corresponding flanges. However, the drawback of the lengthwise oriented construction is that the arc-shaped tower sections can become deformed during transport, which can greatly impede if not prevent the assembly on site. Furthermore, the assembly expense is significantly increased.
Moreover, wind power stations are known in which the rotor and the generator are mounted on a framework tower. This construction has proven to work especially in the case of small and low-height stations. For larger and taller stations, the assembly expense is disproportionately large, since the assembly of the individual pieces of the framework must almost always be done on site and thus a time and cost saving prefabrication is hardly possible.
From DE 10 2006 056 274 A1 there is known a tower of a wind power station which is configured as a latticework tower (framework tower) in the lower region with at least three corner legs and as a tubular tower in the upper region with round cross sections. The upper tower section and the lower tower section are joined to each other by a transition body. The transition body is fashioned in the form of a truncated cone envelope, while the respective corner leg extends into the transition body and is joined there by two lengthwise welds to the outside of the truncated cone envelope.
From DE 103 39 438 A1 there is known a tower for a wind power station, which is likewise formed from a lower tower section in the form of a latticework tower and an upper tower section in the form of a tubular tower. Between these two tower sections is provided a transition body, which joins the lower tower section to the upper tower section. A comparable tower of a wind power station is described in WO 2013/092626 A1.
The aforementioned hybrid towers for wind power stations with a so-called disconnected tower structure, having a lower tower section of framework construction and an upper tower section in the form of tubing, have the drawback that the transition body between the upper and the lower tower section requires an increased assembly expense and does not allow an optimal flow of force.
Therefore, a need exists for improvements to the transition bodies and towers of at least each of the aforementioned and specified kinds of towers for wind turbines so as to lower assembly expenses and improve the flow of forces without causing a disproportionate increase in transportation expenses.